In communication systems pulse signals are employed to transmit information. Specifically, pulse signals are employed in telephone signaling systems to transmit supervisory signals, for example, on-hook, off-hook, wink signals, dial pulses, and the like. All of these supervisory signals actually appear as on-hook and off-hook transitions. In order to insure proper reception of the supervisory signals the transmitted on-hook and off-hook transitions must have at least minimum intervals, commonly referred to as minimum break and make intervals, respectively.
Numerous arrangements have been proposed for realizing the desired minimum break and make intervals. For the most part, these prior known arrangements have employed at least two timing circuits, usually of the analog resistor/capacitor (R/C) type connected in tandem and associated logic arrangements to obtain the desired minimum intervals. Typical examples of pulse correctors utilizing at least two R/C timers are disclosed in U.S. Pat. Nos. 3,544,724, issued to F. S. Pento on Dec. 1, 1970; 3,772,474, issued to O. G. Wisotzky on Nov. 13, 1973; 3,781,482 issued to O. G. Wisotzky on Dec. 25, 1973; 3,908,091, issued to G. C. Waldeck on Sept. 23, 1975; and 3,988,548, issued to G. C. Waldeck on Oct. 26, 1976.
A problem common to these prior known R/C timer arrangements is their use of capacitors and the use of multiple analog timers. Such prior circuits which use analog circuit components are not readily implemented by employing large-scale integration. Indeed, with the advent of large scale integration, it becomes highly desirable to implement the pulse correcting and repeating circuit utilizing digital techniques.
Additionally, in certain applications it is also desirable to provide techniques for inhibiting noise appearing at the input of the correcting and repeating circuit from appearing at the output either as noise or as erroneously generated pulse signals. This is especially important during intervals of transient signal conditions generated, for example, on the so-called M-lead of a telephone inband signaling system.